How to switch from a Developer account to a regular Apple Account for privacy and security settings?

You can register as a Developer using your same personal Apple Account and that will give you access to the Developer forums and also allow you to download the beta updates.

How do I leave the Apple Beta Software Program?

To leave the Apple Beta Software Program, you must first sign in, then click the Leave Program link. If you leave, you will stop receiving emails about the Apple Beta Software Program and will no longer be able to submit feedback with Feedback Assistant.

Unenroll Your Devices - Apple Beta

Just not sure what that has to do with your initial issue of turning on tracking in Privacy & Security. For that issue, verify your birthdate is correct on your account at Update the birthday associated with an Apple Account - Apple Support. If you are using a different Apple Account at Settings > [name on top] > Media & Purchases, you will need to check the details for that account.

If you are in the EU, or other region that mandated Age Assurance laws, you should have the option to submit the required documentation to prove you are an adult. You would not have the option to allow tracking until you have proven you are an adult with the documentation required for that specific region. Check for that recommendation below the name of your Apple Account in Settings.

Another reason you may not be able to turn on Tracking is that changing it may be restricted in Screen Time. Go to Settings > Screen Time > Content & Privacy Restrictions, Allow Apps to Request to Track, and make sure this is set to Allow Changes. If you are a member of a Family Sharing group, the Organizer can override any changes made on your device.

You can create a profile in the Developer forum and that does not mean you have a Developer account or that you are a Developer. You can also create an Account here in the Community Support forum using the same Apple Account. Your Apple Account is the same in both forums and you still sign in with your Apple Account/Password. The only difference is that you probably created a different username on each forum, but neither store your email address, phone number, or actual name where others can see who you are.